Homoousios

Homoousios (Gk.ὁμοούσιος) means "of the same substance," "of the same essence." Homo means "same" and ousia means "essence." The term was used by Athanasius in his correct teaching of the oneness of the Father and the Son in that they are the same substance, the same essence of divinity. The term was used in the Nicene Creed (and creeds thereafter) when it described Jesus as being of the same substance as the Father in its affirmation of the Trinity.